package com.ljc.service.impl;

import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.ljc.dto.Result;
import com.ljc.entity.Shop;
import com.ljc.mapper.ShopMapper;
import com.ljc.service.IShopService;
import com.ljc.utils.CacheClient;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.util.concurrent.TimeUnit;

import static com.ljc.utils.RedisConstants.CACHE_SHOP_KEY;
import static com.ljc.utils.RedisConstants.CACHE_SHOP_TTL;


@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private CacheClient cacheClient;

    @Override
    public Result queryById(Long id) {
        //缓存穿透【封装到工具类中】
        Shop shop = cacheClient.queryWithPassThrough
                (CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        //互斥锁解决缓存击穿
        //Shop shop = queryWithMutex(id);

        //逻辑过期解决缓存击穿【封装到工具类中】
//        Shop shop = cacheClient.queryWithLogicalExpire
//                (CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);
        if (shop == null) {
            return Result.fail("店铺不存在");
        }
        //7、返回
        return Result.ok(shop);
    }

//    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    /**
     * 逻辑过期解决缓存击穿
     * @param id
     * @return
     */
/*    public Shop queryWithLogicalExpire(Long id){
        String key = CACHE_SHOP_KEY + id;
        //1、从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2、判断是否命中
        if (StrUtil.isBlank(shopJson)) {
            //3、未命中，直接返回
            return null;
        }
        //4、命中，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        //5、判断是否过期
        LocalDateTime expireTime = redisData.getExpireTime();
        if (expireTime.isAfter(LocalDateTime.now())){
            //5.1、未过期，直接返回店铺信息
            return shop;
        }
        //5.2、已过期需要缓存重建
        //6、缓存重建
        //6.1、获取互斥锁
        String LockKey = LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(LockKey);
        //6.2、判断是否获取锁成功
        if (isLock) {
            //6.3、获取成功，开启独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    //重建缓存
                    this.saveShop2Redis(id, 20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    //释放锁
                    unlock(LockKey);
                }
            });
        }
        //6.4、无论失败还是成功，返回商铺信息
        return shop;
    }*/

    /**
     * 互斥锁解决缓存击穿
     * @param id
     * @return
     */
    /*public Shop queryWithMutex(Long id){
        String key = CACHE_SHOP_KEY + id;
        //1、从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2、判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //3、存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //判断命中的是否是空值
        if (shopJson != null){
            // 返回一个错误信息
            return null;
        }
        //4、实现缓存重建
        //4.1、获取互斥锁
        String lockKey= LOCK_SHOP_KEY + id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockKey);
            //4.2、是否获取成功
            if (!isLock){
                //4.3、失败，则休眠并重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            //4.4、成功，判断拿到锁后redis中是否有缓存【可能存在拿到锁后其他地方向redis中写入缓存，则无需重建】
            //4.4.1、从redis查询商铺缓存
            shopJson = stringRedisTemplate.opsForValue().get(key);
            //4.4.2、判断是否存在
            if (StrUtil.isNotBlank(shopJson)) {
                //3、存在，直接返回
                return JSONUtil.toBean(shopJson, Shop.class);
            }
            //4.5、根据id查询数据库
            shop = getById(id);
            //模拟重建的延时
            Thread.sleep(200);
            //5、数据库中没有该数据，返回错误
            if (shop == null){
                //将空值写入redis
                stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
                //返回错误信息
                return null;
            }
            //6、存在，写入redis
            stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            //7、释放互斥锁
            unlock(lockKey);
        }
        //8、返回
        return shop;
    }*/

    /**
     * 解决缓存穿透
     * @param id
     * @return
     */
/*    public Shop queryWithPassThrough(Long id){
        String key = CACHE_SHOP_KEY + id;
        //1、从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2、判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //3、存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //判断命中的是否是空值
        if (shopJson != null){
            // 返回一个错误信息
            return null;
        }
        //4、不存在，根据id查询数据库
        Shop shop = getById(id);
        //5、数据库中没有该数据，返回错误
        if (shop == null){
            //将空值写入redis
            stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
            //返回错误信息
            return null;
        }
        //6、存在，写入redis
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //7、返回
        return shop;
    }*/

/*    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", LOCK_SHOP_TTL, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }*/

    /**
     * 数据预热【将热点数据存入redis中】
     */
/*    public void  saveShop2Redis(Long id, Long expireSeconds) throws InterruptedException {
        //1、查询店铺数据
        Shop shop = getById(id);
        Thread.sleep(200);
        //2、封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3、写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(redisData));
    }*/
    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if (id == null) {
            return Result.fail("店铺id为空");
        }
        //1、更新数据库
        updateById(shop);
        //2、删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);
        return Result.ok();
    }
}





